SplitAtlas

Mitsubishi Electric / M-Series SLZ Four-Way Ceiling Cassette

Mitsubishi M-Series SLZ Four-Way Ceiling Cassette 15k Four-Way Cassette Mini-Split

Certified capacity
15,000 BTU/h[2]
SEER2
20.6 SEER2[2]
Heating floor
-4 F[1]
Voltage
230 V[1]
Install path
Professional install

The M-Series SLZ Four-Way Ceiling Cassette 15k is a ceiling cassette for spreading air in four directions from the room center rather than throwing it from one wall. It certifies at 15,000 BTU cooling with 18,000 BTU of 47F heat. The standard outdoor unit favors efficiency and moderate-climate balance, with SEER2 20.6, EER2 12, HSPF2 10.1, and 9,600 BTU at 5F.

The catch is the ceiling. This is a professional Mitsubishi install with ceiling depth, condensate handling, panel clearances, and service access to solve before the quote is real; it is not a quick wall-head swap.

1 zoneProfessional installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

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Error Codes
Mitsubishi Electric four-way ceiling cassette indoor unit for an M-Series SLZ system.

Image: Mitsubishi Pro official product API

Data completeness: 100%
Last sourced
Aug 5, 2026

SplitAtlas score

7.6 / 10

Methodology
Cooling efficiencyBelow average

(20.6 SEER2) among 18k systems

Heating efficiencyAbove average

(10.1 HSPF2) among 18k systems

Cold-weather performanceBottom quartile

(53.3% heat retained at 5F; -4 F heating floor) among 18k systems

NoiseAbove average

(27 dBA indoor min / 51 dBA outdoor) among 18k systems

WarrantyBelow average

(5 yr parts / 7 yr compressor) across the catalogue

Feature setBottom quartile

(3 verified features) across the catalogue

Documentation & partsBelow average

(6 manuals; spec sheet) across the catalogue

Not evaluated

  • Installation accessibility — not applicable (professional install)N/A

    professional install - DIY-accessibility not applicable

  • Price-to-value — not evaluatedN/A

    This is a professionally installed, quote-only system, so we can't score its price. Get an installed quote to compare real cost.

    Get a quote

Key ratings

Rated cooling

15,000BTU/h[2]

Rated heating

18,000BTU/h[2]

Buyer review snapshot

Install difficulty

Professional install
  • Electrical: 230V; MCA 17 A; breaker/fuse 29 A.
  • Line set: connection type not sourced; precharged 25 ft; max 65 ft.

Alternatives

Availability and price context

We could not verify a current retail price for this model. Mitsubishi Electric sells through dealers, so we link to contractor quotes rather than a retail price.

Source date

Model data sourced
Aug 5, 2026
Page reviewed
Aug 2, 2026
Source-backed records
3
Newest source retrieved
Aug 5, 2026

Warranty tiers

Warranty: 5 years parts and 7 years compressor as standard.

Review methodology

Model context

Mitsubishi dealer channel
Mitsubishi Electric is dealer-quoted in this catalog; installed price depends on the local contractor, and the brand context is dealer support and reliability reputation.
Install path
This is professional-install equipment; no verified current retail offer is attached.
Installation context
Ceiling-mounted indoor units need a workable ceiling cavity, panel clearance, drain routing, and service access.

Strengths

  • 20.6 SEER2 / 12 EER2 / 10.1 HSPF2 certified efficiency.
  • 15,000 BTU cassette capacity that distributes air from the ceiling instead of one wall.
  • 11,300 BTU at 17F and 9,600 BTU at 5F give real heating numbers to size against.

Weaknesses

  • Not AHRI cold-climate designated; 5F heat falls to 9,600 BTU, so size carefully in northern winters.

Climate suitability

Minimum heating ambient
-4 F[1]
Rated heating at 5F
9,600 BTU/h[2]
Rated heating at 17F
11,300 BTU/h[2]
Rated heating at 47F
18,000 BTU/h[2]

Specifications

Show
Manufacturer
Mitsubishi Electric
Brand
Mitsubishi Electric
Product line
M-Series SLZ Four-Way Ceiling Cassette
Model number
SLZ-AF15NL-U1 indoor / SUZ-AA15NL-U1 outdoor
Indoor unit model
SLZ-AF15NL-U1
Outdoor unit model
SUZ-AA15NL-U1
Number of zones
1
Max indoor units
not published
Rated cooling capacity
15,000 BTU/h[2]
Rated heating capacity
18,000 BTU/h[2]
Voltage
230 V[1]
MCA
17 A[1]
Maximum fuse or breaker size
29 A[1]
Breaker needed
not published
SEER2
20.6 SEER2[2]
EER2
12 EER2[2]
HSPF2 (Region 4)
10.1 HSPF2[2]
HSPF2 (Region 5)
not published
COP
not published
COP at 47F
3.3 COP[1]
COP at 5F
2 COP[2]
Minimum outdoor heating temperature
-4 F[1]
Minimum outdoor cooling temperature
14 F[1]
Maximum outdoor temperature
115 F[1]
Indoor noise range
heating 27 , 34 , 39[1]
Outdoor noise rating
51 dBA[1]
Indoor weight
31 lb[1]
Outdoor weight
81 lb[1]
Refrigerant
R-454B[1]
Refrigerant charge
not published
Manufacturer coverage
not published
Line-set size
1/4 in liquid / 1/2 in suction
Included line-set length
Mitsubishi submittals publish line-size and maximum/precharged piping data; the installing contractor supplies the line set.
Maximum line-set length
65 ft[1]
Max line set per indoor
not published
Maximum elevation difference
40 ft[1]
Max height between indoor units
not published
Wi-Fi support
supported[1]
Energy Star status
ENERGY STAR certified[2]
AHRI certification number
215734901[2]
Warranty
Standard: 5 yr parts / 7 yr compressor (licensed HVAC contractor installation). METUS residential warranty terms list a standard 5-year parts and 7-year compressor term when installed by a licensed HVAC contractor, with enhanced registered coverage available under program conditions.
Install path
Professional install
Retail price
Mitsubishi Electric sells through dealers, so we link to contractor quotes rather than a retail price.
Available retailers
not published
Manual links
AHRI public detail 215734901, BH79A782H03.pdf, MitsubishiPro product record SLZ-AF15NL, MitsubishiPro product record SUZ-AA15NL, SLZ-AF15NL / SUZ-AA15NL Mitsubishi Electric submittal, METUS Residential M-Series, P-Series and SMART MULTI Limited Warranty Statement
Specification sheet
SLZ-AF15NL / SUZ-AA15NL Mitsubishi Electric submittal
Last sourced date
Aug 5, 2026

Electrical requirements

Show
Voltage
230 V[1]
Voltage range
not published
Phase
1[1]
Frequency
60 Hz[1]
MCA
17 A[1]
Breaker needed
not published
Maximum breaker size
29 A[1]
Maximum fuse size
29 A[1]
Maximum cooling current
not published
Maximum heating current
not published
Manufacturer wire notes
14 AWG indoor-outdoor[1]

Installation considerations

Show
Liquid line
1/4 in[1]
Suction line
1/2 in[1]
Line connection type
not published
Precharged length
25 ft[1]
Included line-set length
Mitsubishi submittals publish line-size and maximum/precharged piping data; the installing contractor supplies the line set.
Maximum line-set length
65 ft[1]
Max line set per indoor
not published
Max height between indoor units
not published
Indoor dimensions
22-7/16 x 22-7/16 x 9-21/32 in[1]
Outdoor dimensions
31-1/2 x 11-1/4 x 21-5/8 in[1]
Indoor weight
31 lb[1]
Outdoor weight
81 lb[1]
Drain size
not published

Related systems and guides

Frequently asked questions

Can I install the Mitsubishi Electric M-Series SLZ Four-Way Ceiling Cassette 15,000 BTU R-454B 208/230V (SLZ-AF15NL / SUZ-AA15NL) myself, or do I need a pro?
Mitsubishi Electric M-Series SLZ Four-Way Ceiling Cassette 15,000 BTU R-454B 208/230V (SLZ-AF15NL / SUZ-AA15NL) is built for professional installation: the line set must be flared, evacuated, and charged, which requires EPA-certified refrigerant handling. Installing it outside the manufacturer's requirements can void the warranty, so budget for a qualified HVAC installer.
Will the Mitsubishi Electric M-Series SLZ Four-Way Ceiling Cassette 15,000 BTU R-454B 208/230V (SLZ-AF15NL / SUZ-AA15NL) keep heating in a cold winter?
The manufacturer publishes 9,600 BTU/h of heating output at 5F. Rated heating operation extends down to -4 F. Certified heating efficiency is 10.1 HSPF2. Match those numbers against your climate's design temperature - in cold regions, output at 5F matters far more than the nameplate capacity measured at 47F.
What electrical circuit does the Mitsubishi Electric M-Series SLZ Four-Way Ceiling Cassette 15,000 BTU R-454B 208/230V (SLZ-AF15NL / SUZ-AA15NL) need?
Published electrical requirements: 230 V voltage, 17 A minimum circuit ampacity, and 29 A maximum breaker or fuse sizing. Confirm the final circuit against the unit nameplate and local code with a licensed electrician.
How far can the outdoor unit be from the indoor head?
The published maximum line-set length is 65 ft, and the included line set comes pre-charged for 25 ft. Longer runs than the included set allows typically mean added refrigerant and a pro visit, so measure the planned routing before ordering.
What warranty does the Mitsubishi Electric M-Series SLZ Four-Way Ceiling Cassette 15,000 BTU R-454B 208/230V (SLZ-AF15NL / SUZ-AA15NL) carry?
The manufacturer publishes these warranty tiers: Standard: 5 yr parts / 7 yr compressor (licensed HVAC contractor installation). Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.

Data sources

Show
  1. Mitsubishi Electric Trane HVAC US LLC: SLZ-AF15NL / SUZ-AA15NL Mitsubishi Electric submittalSourced - manufacturer technical document

    Covers Frequency, electrical_spec.guaranteed_voltage_range, electrical_spec.indoor_mca_amps, Maximum breaker size, Maximum fuse size, Minimum circuit ampacity and more

  2. Air-Conditioning, Heating, and Refrigeration Institute: AHRI public detail 215734901Sourced - AHRI directory

    Covers AHRI certification number, performance_spec.cold_climate_designation, Rated cooling capacity, COP at 5F, EER2, Energy Star status and more

  3. Mitsubishi Electric Trane HVAC US LLC: METUS Residential M-Series, P-Series and SMART MULTI Limited Warranty StatementSourced - secondary source

    Covers Legacy compressor warranty value, Legacy warranty value, Standard compressor warranty, Standard warranty conditions, Standard parts warranty, Warranty notes

Last updated

Aug 2, 2026